ABSTRACT: The Japanese shore crab Hemigrapsus sanguineus (de Haan) was recently introduced to the northeast coast of the USA. The crab has established intertidal populations extending throughout the Middle Atlantic Bight. This study defines early-life-history characteristics that are germane to range extension in this species. Results of the investigation showed that the spawning season of H. sanguineus continues for at least 4 mo in the southern Middle Atlantic Bight. This is considerably longer than the spawning seasons of co-occurring native crabs. Eggs hatch about 14 d after extrusion, and females have the potential to produce several broods each year. Zoeal larvae are tolerant of a wide range of temperature/salinity combinations, and mean duration of zoeal development ranges from approximately 16 d at 25°C to 55 d at 15°C. At 25°C zoeae are capable of development to the megalopa stage at salinities as low as 15o/oo. At lower temperatures the zoeae require salinities above 20o/oo. The megalopa stage appears to have more stringent temperature/salinity requirements, which may restrict H. sanguineus to rocky shores of the coastal ocean and the adjacent high-salinity regions of the estuary. Under these conditions megalopae molt to the first juvenile stage in approximately 25 d post hatching. Newly metamorphosed crabs reach the fifth juvenile instar in 35 d. Dry-weight growth of zoeal larvae and early stage juveniles is exponential at respective rates of 23 and 8% of body weight per day.

KEY WORDS: Non-indigenous · Exotic · Crab · Larvae · Juvenile · Growth

Published in MEPS Vol. 170 (1998) on September 3
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1998